Comparison of the antimicrobial effect of chlorhexidine and saline for irrigating a contaminated open fracture model.

OBJECTIVES The objective of this study is to compare antimicrobial effect of irrigation with chlorhexidine gluconate (CHG) to saline in an animal model. METHODS This study used a segmental defect rat femur model contaminated with Staphylococcus aureus and treated 6 hours after injury with debridement and irrigation with 60 mL of fluid delivered at low pressure. In study groups of 10 animals each, 3 concentrations of CHG (0.5%, 0.05%, and 0.005%) were used and a group irrigated with 0.05% CHG and then saline and a control group treated with saline only. After irrigation the wounds were closed, and the rats were recovered. Fourteen days later, bone and implants were harvested for separate microbiological analysis. RESULTS There was no statistical difference detected between the subsequent presence or quantity of bacteria after irrigation, with aqueous CHG at a range of concentrations comparing irrigation with saline alone. CONCLUSIONS This study does not support the use of CHG as an irrigant. This may be due to the antibacterial effect of CHG being offset by the associated host tissue toxicity. Host tissue damage from high irrigation pressures and cytotoxic solutions has been shown to allow bacteria to thrive. We believe this is due to a "rebound" of bacteria growth in a wound bed containing small quantities of necrotic tissue damaged by CHG exposure.